IT'S the last thing any elected official wants to do. But the mayor of South Africa's largest city has warned residents their town is fast approaching "Day Zero".

"We have reached a point of no return," Cape Town mayor, Patricia de Lille, conceded.

She was talking about the city running out of water. An event which is predicted to happen in less than 75 days. Day Zero - the day the taps run dry - is currently forecast to occur on April 12.

The city is in the midst of its worst drought in a century and as the situation grows increasingly dire, officials fear contingency plans won't be enough to prevent the city descending into chaos.

Most of the metropolitan area's nearly 4 million residents will have to collect allotments of water from 200 distribution points - a situation that the mayor fears could lead to anarchy.

Strict water restrictions are already in force, limiting the maximum use per person to 50 litres per day.

Currently water levels at dams in the region are sitting just above 17 per cent full. When levels drop to 13.5 per cent, residents will have to queue for daily rations of 25 litres.

Police and the army will be on standby to be deployed to prevent any civil unrest.

and so it begins. Guy took every single bottle of water left in this PnP (Note empty shelf behind him) A young woman came up to him & asked if she could have one. He straight up said "No They are all mine". Next few moths are going to get pretty interesting. #WaterCrisis#DayZeropic.twitter.com/sMWHLKwCXl

According to Waterwise, a typical shower uses between 10 and 15 litres per minute while a single toilet flush can consume almost as much. For Capetonians, these things are fast becoming a luxury.

The BBC's Mohammed Allie is currently living in the city and described how his household is scrimping on water amid the crisis.

"My wife does not use the shower any more. Instead, she boils about 1.5 litres of water and mixes it with about a litre of tap water to have her daily wash while the rest of us catch the slow running water in a bucket for re-use in the toilet cistern," he wrote.

Water has clearly become "the new gold" of Cape Town, he said.

Water from Monday hair wash ready to go into the toilet cistern. No-one in Cape Town should be using fresh water to flush. Turn off the cistern tap. Fill it with grey water and flush as little as possible. pic.twitter.com/Sc90LLqnKs

Officials have told residents to conserve water and stockpile bottled water in "sensible" amounts but warned against panic buying.

"For their own benefit, it's a good idea to keep some water stored somewhere," said James-Brent Styan, a local government spokesman. "They can buy water at some shops or buy online and have it delivered. We'd like to urge people not to panic and buy all the water at the shops, they don't need to do that at this stage."

Although pictures posted to social media clearly show some residents have done just that.

Ms de Lille, whose position as mayor is under threat, has derided some residents for not adhering to the strict water restrictions in place.

"Despite our urging for months, 60 per cent of Capetonians are callously using more than 87 litres per day," she said last week.

"It is quite unbelievable that a majority of people do not seem to care and are sending all of us headlong towards Day Zero."

An advertisement shared by the city of Cape Town council on social media.

GROWING THREAT OF WATER SCARCITY

Water is absolutely fundamental to life, which makes the increasingly loud warnings about global water scarcity so concerning.

"Our planet, the human family and life in all its myriad forms on Earth are in the throes of a water crisis that will only get worse over the coming decades," Bolivian President Evo Morales told the UN Security Council in June.

According to the World Bank, if current patterns of consumption continue unabated, two-thirds of the world's population will be facing water shortages as a daily reality by 2025.

Adelaide University's Professor Mike Young who is a specialist in water policy says the worrying trend is taking place all over the globe.

"What's happening bit by bit is that water scarcity is becoming increasingly common all around the world, no matter where you look as country after country hits the limit of what it can use," he told news.com.au last year.

"Whether that's in Australia, California, China, India, Pakistan, or right throughout Africa."

Bare sand and dried tree trunks standing out at Theewaterskloof Dam, which has less than 20 per cent of it's water capacity, near Villiersdorp, about 108km from Cape Town. Picture: Rodger Bosch

While Earth may be covered in water, freshwater - the kind we care about - actually only represents 2.5 per cent of that. And almost 99 per cent of freshwater it is trapped in hard to reach places like glaciers and snowfields.

In the end, less than 1 per cent of the planet's water is actually available to fuel and feed the world's more than 7.6 billion people.

Groundwater is being pumped so aggressively that land is sinking. Some neighbourhoods in Beijing (the world's fifth most water-stressed city) are sinking at as much as 10cm a year.

While big data and emerging technologies including fast-to-deploy desalination and water recycling systems are part of the solution, Professor Young says more sophisticated water sharing agreements between countries are needed to address the issue.

On Wednesday, the World Wildlife Fund called on Cape Town to introduce emergency by-laws for groundwater sharing if April arrived with no rain.

"Life beyond Day Zero will present exceptional circumstances and we hope that emergency by-laws will be brought in to enable Capetonians to use and share groundwater with neighbours for more uses in order to relieve the burden on the city's emergency points of distribution," the organisation said in a press release.

For now, while officials and residents prepare for the worst, the countdown to Day Zero continues.

People queue to collect water from a natural spring in Cape Town, South Africa, Monday, January 22, 2018 as the city suffers from one of the worst droughts in recent history. Picture: Anwa Essop